# Patent

## Title
Method and a device for sequencing the ZC sequences of the random access channel

## Abstract

The present invention discloses a method and a device for sequencing the ZC sequences of the random access channel. The method for sequencing the ZC sequences includes the following steps: Step 202, ZC sequences are divided into a plurality of groups according to the cubic metrics of the ZC sequences; Step 204, the ZC sequences are sequenced, according to the maximum cyclic shift supported by the ZC sequences under a high speed circumstance, within each group to form a plurality of sub-groups; and Step 206, the ZC sequences within each of the plurality of sub-groups are sequenced according to the cubic metrics of the ZC sequences, wherein, the adjacent sub-groups in the same group are sequenced in different orders, while the sub-groups at the boundary of the two adjacent groups are sequenced in the same order. Thereby, the sequences could be assigned according to the CMs, and the sequence fragments could be collected for use.

## Background
FIELD OF THE INVENTION
The present invention relates to communication field, in particular to a method and a device for sequencing the ZC sequences of the random access channel.
BACKGROUND OF THE INVENTION
In Long Term Evolution (LTE for short) system, cyclic shift sequences of Zadoff-Chu (ZC for short) sequences are used as preambles by the Random Access Channel (RACH for short). These cyclic shift sequences are also referred to as Zero Correlation Zone (ZCZ for short) sequences.
In practical systems, after a mobile phone is powered on, firstly, downlink synchronization is first performed, and then the detection of the Broadcast Channel (BCH for short) is initiated. A base station informs, via the BCH channel, the mobile phone the index and the step length of the cyclic shift of the first ZC sequence available for the RACH of the current cell. According to the index, the mobile phone makes use of certain mapping rule to calculate the serial number of the corresponding ZC sequence, and then, generates usable ZCZ sequences according to the step length of the cyclic shift and a certain “cyclic shift limitation rule”. If the number of the ZCZ sequences is smaller than a certain threshold P, the mobile phone automatically increments the sequence index, and continuously generates the ZCZ sequences using the next ZC sequence, until the total number of the ZCZ sequences is larger than or equal to P. Finally, the mobile phone randomly selects one sequence from all the generated usable ZCZ sequences as a preamble to be sent.
In a high speed circumstance, the frequency offset caused by Doppler Effect will generate, during the process of the preamble detection, a correlation peak alias, which will lead to a timing offset and a false detection. This problem is settled in LTE system through limiting the use of some cyclic shifts according to a certain rule, which is the mentioned “cyclic shift limitation rule”. Meanwhile, the cyclic shift limitation rule also limits the maximum cyclic shift NCS corresponding to each ZC sequence, and this maximum cyclic shift directly determines the maximum cell radius supported by each ZC sequence. Supposing that the distance between the correlation peak and the correlation peak alias thereof is du, the relation between the maximum cyclic shift NCS and du is:

NCS=min(du, NZC−2·du)  (1)

wherein, NZC is the length of a ZC sequence, du can be calculated by the following formula:




  
    
      
        du
        =
        
          {
          
            
              
                
                  
                    
                      
                        m
                        ·
                        
                          N
                          ZC
                        
                      
                      -
                      1
                    
                    u
                  
                  ,
                
              
              
                
                  
                    when
                    ⁢
                    
                      
                    
                    ⁢
                    
                      
                        
                          m
                          ·
                          
                            N
                            ZC
                          
                        
                        -
                        1
                      
                      u
                    
                  
                  ≤
                  
                    floor
                    ⁡
                    
                      (
                      
                        N
                        /
                        2
                      
                      )
                    
                  
                
              
            
            
              
                
                  
                    
                      N
                      ZC
                    
                    -
                    
                      
                        
                          m
                          ·
                          
                            N
                            ZC
                          
                        
                        -
                        1
                      
                      u
                    
                  
                  ,
                
              
              
                
                  
                    when
                    ⁢
                    
                      
                    
                    ⁢
                    
                      
                        
                          m
                          ·
                          
                            N
                            ZC
                          
                        
                        -
                        1
                      
                      u
                    
                  
                  >
                  
                    floor
                    ⁡
                    
                      (
                      
                        N
                        /
                        2
                      
                      )
                    
                  
                
              
            
          
        
      
    
    
      
        (
        2
        )
      
    
  




wherein, u is the serial number of the ZC sequence, and m is the minimum positive integer which makes




  
    
      m
      ·
      
        N
        ZC
      
    
    -
    1
  
  u




a positive integer.

The mapping process between the indices and the serial numbers of the ZC sequences is actually the process of re-sequencing the ZC sequences. At present, there are mainly two sequencing methods: one is to sequence according to the cubic metric (CM for short, it is a standard for measuring the Peak-to-Average Power Ratio of the emitted data, the larger the CM is, the higher the Peak-to-Average Power Ratio is) of the ZC sequences, and the other is to sequence according to the maximum cell radius supported by each ZC sequence. The first method is advantageous in that network planning can be conveniently performed according to the CM of a root sequence so as to assign the sequences with smaller CMs to the cells with larger radius, and the sequences with close CMs to the same cell. Its shortcoming lies in that sequence fragments will be generated, which will cause the waste of the sequences. In other words, during the process of generating the ZCZ sequences with the continuous incrementation of the sequence index, if the maximum cell radius supported by a ZC sequence is smaller than the radius of the current cell, this sequence neither could be used by the current cell, nor it could be used by other cells having radiuses smaller than the maximum cell radius supported by this ZC sequence (this is because that the index is continuously incremental, as shown in FIG. 1). The second method is advantageous in avoiding the generation of the sequence fragments, that is disadvantageous in that the CMs of the ZC sequences assigned to a cell differs greatly from each other so that sequence planning can not be performed according to the CM.
SUMMARY OF THE INVENTION
In view of the above mentioned one or more problem, the present invention provides a method and a device for sequencing the ZC sequences of the random access channel.
The method for sequencing the ZC sequences of the random access channel according to the embodiments of the present invention comprises the following steps: Step 202, Nq ZC sequences are divided into a plurality of groups according to the cubic metrics of the ZC sequences; Step 204, the ZC sequences are sequenced, according to the maximum cyclic shift supported by the ZC sequences under a high speed circumstance, within each group to form a plurality of sub-groups; and Step 206, the ZC sequences are sequenced within each of the plurality of sub-groups according to the cubic metrics of the ZC sequences, wherein, the adjacent sub-groups in the same group are sequenced in different orders, while the sub-groups at the boundary of the two adjacent groups are sequenced in the same order.
Wherein, in Step 202, Nq ZC sequences are divided into G groups, wherein, 1≦G≦Nq, the relation between the serial number of each of the plurality of groups and the cubic metrics of the ZC sequences in each of the plurality of groups is: the cubic metrics of the ZC sequences in Group i are smaller than the cubic metrics of the ZC sequences in Group i+1, or the cubic metrics of the ZC sequences in Group i are larger than the cubic metrics of the ZC sequences in Group i+1. Specifically, Nq ZC sequences may be divided into two groups according to the cubic metrics of Quadrature Phase Shift Keying.
Wherein, in Step 202, firstly, Nq ZC sequences are sequenced, in the decreasing order or in the increasing order, according to the cubic metrics of the ZC sequences, and then, the sequencing result is divided into a plurality of groups according to one or more cyclic shift thresholds.
Wherein, the sequencing process in Step 204 may be performed in the increasing order or in the decreasing order, and the adjacent groups are sequenced in different orders.
Wherein, the sequencing process in Step 204 needs to be performed according to a certain granularity. The granularity of the cyclic shift of Group g is Pg={P1g, P2g, . . . , Psg}, and Pig<Pi+1g, thus, (1) the sequencing performed in the increasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Pi+1g, and larger than or equal to Pig, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than P1g, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg; (2) the sequencing performed in the decreasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Ps−i+2g and larger than or equal to Ps−i+1g, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Pig.
Wherein, the maximum cyclic shift NCS=min(du, NZC−2·du), wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of the ZC sequence. The distance between the correlation peak and the correlation peak alias thereof is




  du
  =
  
    {
    
      
        
          
            
              
                
                  
                    m
                    ·
                    
                      N
                      ZC
                    
                  
                  -
                  1
                
                u
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ≤
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
        
          
            
              
                
                  N
                  ZC
                
                -
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              >
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
      
      ,
    
  




wherein, u is the serial number of the ZC sequence, and m is the minimum positive integer which makes





  
    
      m
      ·
      
        N
        ZC
      
    
    -
    1
  
  u




a positive integer.

The device for sequencing the ZC sequences of the random access channel according to the embodiments of the present invention comprises: a first group dividing unit, configured to divide Nq ZC sequences into a plurality of groups according to the cubic metrics of the ZC sequences of the random access channel; a to second group dividing unit, configured to sequence the ZC sequences within each group to form a plurality of sub-groups, according to the maximum cyclic shift supported by the ZC sequences under a high speed circumstance; and a sequencing unit, configured to sequence the ZC sequences in each of the plurality of sub-groups according to the cubic metrics of the ZC sequences, wherein, the adjacent sub-groups in the same group are sequenced in different orders, while the sub-groups at the boundary of the two adjacent groups are sequenced in the same order.
Wherein, the first group dividing unit divides Nq ZC sequences into G groups, wherein, 1≦G≦Nq, the relation between the serial number of each of the plurality of groups and the cubic metrics of the ZC sequences in each of the plurality of group is: the cubic metrics of the ZC sequences in Group i are smaller than the cubic metrics of the ZC sequences in Group i+1, or the cubic metrics of the ZC sequences in Group i are larger than the cubic metrics of the ZC sequences in Group i+1. Specifically, the first group dividing unit divides the Nq ZC sequences into two groups using the cubic metrics of Quadrature Phase Shift Keying as a threshold.
Wherein, the second group dividing unit divides the ZC sequences in each sub-group into a plurality of sub-groups according to one of the following principles: the maximum cyclic shift supported by the ZC sequences in Sub-group i under the high speed circumstance is smaller than the maximum cyclic shift supported by the ZC sequences in Sub-group i+1 under the high speed circumstance, the maximum cyclic shift supported by the ZC sequences in Sub-group i under the high speed circumstance is larger than the maximum cyclic shift supported by the ZC sequences in Sub-group i+1 under the high speed circumstance, wherein, the second group dividing unit applies different principles to the sub-groups in adjacent groups.
Wherein, the sequencing process of the second group dividing unit may be performed in the increasing order or in the decreasing order, and the adjacent groups should be sequenced in different orders.
Wherein, the sequencing process of the second group dividing unit needs to be performed according to a certain granularity. The granularity of the cyclic shift of Group g is Pg={P1g, P2g, . . . , Psg}, and Pig<Pi+1g, thus, (1) performing the sequencing in the increasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Pi+1g, and larger than or equal to Pig, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than P1g, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg; (2) performing the sequencing in the decreasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Ps−i+2g, and larger than or equal to Ps−i+1g, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than P1g.
Wherein, the maximum cyclic shift NCS=min(du, NZC−2·du), wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of the ZC sequence. The distance between the correlation peak and the correlation peak alias thereof is




  du
  =
  
    {
    
      
        
          
            
              
                
                  
                    m
                    ·
                    
                      N
                      ZC
                    
                  
                  -
                  1
                
                u
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ≤
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
        
          
            
              
                
                  N
                  ZC
                
                -
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              >
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
      
      ,
    
  




wherein, u is the serial number of the ZC sequence, and m is the minimum positive integer which makes





  
    
      m
      ·
      
        N
        ZC
      
    
    -
    1
  
  u




a positive integer.

The present invention not only enables the assignment of the sequences according to the CMs, but also enables the collection of the sequence fragments for use, so that the generation of sequence fragments can be avoided. Meanwhile, the present invention is fully compatible to the first and the second re-sequencing methods described in the Background of the Invention, without introducing any extra signaling cost.



BRIEF DESCRIPTION OF THE DRAWINGS
The drawings illustrated here provide a further understanding of the present invention and form a part of the present application. The exemplary embodiments and the description thereof are used to explain the present invention without unduly limiting the scope of the present invention, wherein:
FIG. 1 is a schematic diagram of the generation of the sequence fragments in relevant techniques;
FIG. 2 is a flowchart of the method for sequencing the ZC sequences of the random access channel according to the embodiments of the present invention;
FIG. 3 is a schematic diagram of Step 202 in the method illustrated in FIG. 2;
FIG. 4 is a schematic diagram of Step 204 in the method illustrated in FIG. 2;
FIG. 5 is a schematic diagram of Step 206 in the method illustrated in FIG. 2 (in view of the cubic metric);
FIG. 6 is a schematic diagram of Step 206 in the method illustrated in FIG. 2 (in view of the maximum cyclic shift supported by the ZC sequences); and
FIG. 7 is a block diagram of the device for sequencing the ZC sequences of the random access channel according to an embodiment of the present invention.



DETAILED DESCRIPTION OF THE EMBODIMENTS
The embodiments of the present invention will be described hereinafter in detail in conjunction with the drawings thereof.
The method for sequencing the ZC sequences of the random access channel according to an embodiment of the present invention is described with reference to FIG. 2. As shown in FIG. 2, the method for sequencing the ZC sequences comprises the following steps:
Step 202, the ZC sequences are divided into a plurality of groups according to the cubic metrics of the ZC sequences. Specifically, there are various principles for the group division. For example, the CM of data modulated using Quadrature Phase Shift Keying (QPSK for short) is 1.2 dB, and this value can be used as a threshold to divide the ZC sequences into two groups: the CMs of the ZC sequences in the first group is smaller than or equal to 1.2 dB; and the CMs of the ZC sequences in the second group is larger than 1.2 dB. Wherein, the following method can be used to carry out this step: sequencing the cubic metrics of the ZC sequences in the increasing order; and dividing the sequencing result into two groups using the cubic metric (1.2 dB) of QPSK as a threshold.
Step 204, the ZC sequences are sequenced, according to the maximum cyclic shift supported by the ZC sequences under a high speed circumstance, within each group to form a plurality of sub-groups. The sequencing process may be performed in the increasing order or in the decreasing order, and the adjacent groups (the groups obtained through Step 202) shall be sequenced in different orders. Moreover, the sequencing process needs to be performed according to a certain granularity. The granularity of the cyclic shift of Group g is Pg={P1g, P2g, . . . , Psg}, and Pig<Pi+1g, thus, (1) the sequencing performed in the increasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Pi+1g, and larger than or equal to Pig, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than P1g, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg; (2) the sequencing performed in the decreasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Ps−i+2g and larger than or equal to Ps−i+1g, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than P1g.
Step 206, in each sub-group, the sequencing is performed according to the CM values of the ZC sequences, and the adjacent sub-groups in the same group are sequenced in different orders, while the sub-groups at the boundary of the two adjacent groups are sequenced in the same order.
Wherein, since performing the sequencing according to the maximum cell radius supported by the ZC sequences only needs to know the relative relation between the maximum cell radiuses supported by respective ZC sequences, and since the maximum cell radius supported by each ZC sequence is directly determined by the maximum cyclic shift NCS of each ZC sequence, the sequencing process is equivalent to performing a sequencing according to NCS. Wherein, NCS=min(du, NZC−2·du), du is the distance between the correlation peak and the correlation peak alias thereof, and NZC is the length of a ZC sequence. The distance between the correlation peak and the correlation peak ali as thereof is




  du
  =
  
    {
    
      
        
          
            
              
                
                  
                    m
                    ·
                    
                      N
                      ZC
                    
                  
                  -
                  1
                
                u
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ≤
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
        
          
            
              
                
                  N
                  ZC
                
                -
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              >
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
      
      ,
    
  




wherein, u is the serial number of the ZC sequence, and m is the minimum positive integer which makes





  
    
      m
      ·
      
        N
        ZC
      
    
    -
    1
  
  u




a positive integer.

For example, the length NZC of the ZC sequence is 839, and each cell needs to generate 64 usable ZCZ sequences. Firstly, the ZC sequences are divided into two groups according to the CM value (1.2 dB) of the QPSK, wherein, the CM value of the first group is smaller than 1.2 dB, and the CM value of the second group is larger than 1.2 dB (as shown in FIG. 3); secondly, the sequencing is performed according to the granularity {15, 18, 22, 26, 32, 38, 46, 55, 68, 82, 100, 128, 158, 202, 237}, and according to the maximum cyclic shift supported by the ZC sequences under the high speed circumstance, and the sequencing is performed in the increasing order in the low CM group, while in the decreasing order in the high CM group, and the ZC sequences are divided into 16 sub-groups in each group (as shown in FIG. 4); finally, the sequencing is performed in each sub-group according to the CMs of the sequences, and the adjacent sub-groups are sequenced in different orders (as shown in FIGS. 5 and 6). The sequencing result is shown in table 1






















TABLE 1





SG1
SG2
SG3
SG4
SG5
SG6
SG7
SG8
SG9
SG10
SG11
SG12
SG13
SG14
SG15
SG16















low cubic metric group






















129
56
80
35
808
24
86
744
217
12
228
832
687
5
225
3


710
783
759
804
31
815
753
95
622
827
611
7
152
834
614
836


140
112
42
766
811
791
761
202
128
816
227
831
144
806
615
820


699
727
797
73
28
48
78
637
711
23
612
8
695
33
224
19


719
148
40
693
30
771
796
649
697
34
132
823
134
788
618
817


120
691
799
146
809
68
43
190
142
805
707
16
705
51
221
22


629



812
74
39
658
122
37
706
792
138
764
220
798


210



27
765
800
181
717
802
133
47
701
75
619
41


168



29
661
819
702
203
793
143
64
640
740
127
38


671



810
178
20
137
636
46
696
775
199
99
712
801


84




703
818
125
721
207
704
57
162
743
147
44


755




136
21
714
118
632
135
782
677
96
692
795


105






151
729
660
161
735
176
97
124
52


734






688
110
179
678
104
663
742
715
787


746







89
694
201
101
119
166
193
45


93







750
145
638
738
720
673
646
794


70







736
709
666
108
681
172
205
63


769







103
130
173
731
158
667
634
776


779







61
223
733
631
164
664
633
772


60







778
616
106
208
675
175
206
67


2







784

756
655
665
652
723
72


837







55

83
184
174
187
116
767


1







824

748
197
668
676
679
76


838







15

91
642
171
163
160
763










825

66
648
170
185
186
745










14

773
191
669
654
653
94












53
718
87
639
167
737












786
121
752
200
672
102












10
141
670
114
760
90












829
698
169
725
79
749












9
149
751
189
754
109












830
690
88
650
85
730













623
107
724
77
165













216
732
115
762
674













218
758
194
92
728













621
81
645
747
111














82
195
781
209














757
644
58
630














100
647
62
204














739
192
111
635














98
182
69
117














741
657
770
722














768
682
54
651














71
157
785
188














59
156
803
680














780
683
36
159














65
211
807
198














774
628
32
641














789
154
25
113














50
685
814
726














49
716
821
656














790
123
18
183














813
700
828
659














26
139
11
180














822
212
835
177














17
627
4
662














826
686

643














13
153

196














6
213

155














833
626

684















215

625















624

214















689

126















150

713

















708

















131

















219

















620

















617

















222

















613

















226







high cubic metric group






















609
323
237
509
257
346
608
546
242
317
603
484
604
530
367
503


230
516
602
330
582
493
231
293
597
522
236
355
235
309
472
336


232
320
600
338
566
500
260
288
274
307
303
434
572
265
296
534


607
519
239
501
273
339
579
551
565
532
536
405
267
574
543
305


577
334
244
498
584
351
268
284
402
553
356
435
302
233

466


262
505
595
341
255
488
571
555
437
286
483
404
537
606

373


587
359
243
499
254
306
563
471
383
552

433



280


252
480
596
340
585
533
276
368
456
287

406



559


418
544
275
497
245
550
430
253
482
573





560


421
295
564
342
594
289
409
586
357
266





279


416
454
561
301
588
439
398
583
510
578





419


423
385
278
538
251
400
441
256
329
261





420


426
292
589
366
412
461
549
263







240


413
547
250
473
427
378
290
576







599


428
291
246
401
467
465
535








258


411
548
593
438
372
374
304








581


463
381
417
468
557
415
308








610


376
458
422
371
282
424
531








229


444
399
248
408
436
569
358


395
440
591
431
403
270
481


283
380
445
464
396
598
316


556
459
394
375
443
241
523


285
442
393
249
447


554
397
446
590
392


379
470
370
269
448


460
369
469
570
391


449
462
365
238
457


390
377
474
601
382


363
429
300
605
389


476
410
539
234
450


455
407
299

294


384
432
540

545


451
281
475

542


388
558
364

297


386
425
362

528


453
414
477

311


478
592
541

344


361
247
298

495


452
562
527

345


387
277
312

494


360
568
313

318


479
271
526

521


529
272
525

331


310
567
314

508


485
264
353

514


354
575
486

325


511
580
487

321


328
259
352

518


524

343


315

496


337

512


502

327


349

350


490

489


504

326


335

513


515

319


324

520




332




507




506




333




491




348




492




347




517




322









After the above sequencing process is completed, the mapping relation between the sequence indices and the serial numbers of the ZC sequences can be obtained. As to a practical system, the mapping relation can be stored in the memories of a mobile phone and a base station. After the base station informs, via the BCH channel, the mobile phone the sequence index, the mobile phone can find the serial number of the ZC sequence corresponding to the index according to the mapping relation, and then generate usable ZCZ sequences according to the step length of cyclic shift and the cyclic shift limitation rule. If the number of the ZCZ sequences is smaller than 64, the mobile phone increments the index, and continuously generates ZCZ sequences using the next ZC sequence until the total number of the ZCZ sequences reaches 64. Finally, the mobile phone randomly selects one sequence from all the generated ZCZ sequences as a preamble to be sent.
The device for sequencing the ZC sequences of the random access channel according to an embodiment of the present invention is described with reference to FIG. 7. As shown in FIG. 7, the device for sequencing the ZC sequences of the to random access channel comprises: a first group dividing unit 702, configured to divide Nq ZC sequences into a plurality of groups according to the cubic metrics of the ZC sequences of the random access channel; a second group dividing unit 704, configured to sequence the ZC sequences within each group to form some sub-groups according to the maximum cyclic shift supported by the ZC sequences under high speed circumstance; and a sequencing unit 706, configured to sequence the ZC sequences in each of the plurality of sub-groups according to the cubic metrics of the ZC sequences, wherein, the adjacent sub-groups in the same group are sequenced in different orders, while the sub-groups at the boundary of the two adjacent groups are sequenced in the same order.
Wherein, the first group dividing unit divides the Nq ZC sequences into G groups, wherein, 1≦G≦Nq, the relation between the serial number of each group and the cubic metrics of the ZC sequences in each group is: the cubic metrics of the ZC sequences in Group i is smaller than the cubic metrics of the ZC sequences in Group i+1, or the cubic metrics of the ZC sequences in Group i is larger than the cubic metrics of the ZC sequences in Group i+1. Specifically, the first group dividing unit divides the Nq ZC sequences into two groups using the cubic metrics of Quadrature Phase Shift Keying as a threshold.
Wherein, the second group dividing unit divides the ZC sequences in each sub-group into a plurality of sub-groups according to one of the following principles: the maximum cyclic shift supported by the ZC sequences in Sub-group i under the high speed circumstance is smaller than the maximum cyclic shift supported by the ZC sequences in Sub-group i+1 under the high speed circumstance, the maximum cyclic shift supported by the ZC sequences in Sub-group i under the high speed circumstance is larger than the maximum cyclic shift supported by the ZC sequences in Sub-group i+1 under the high speed circumstance, wherein, the second group dividing unit applies different principles to the sub-groups in adjacent groups.
Wherein, the sequencing process of the second group dividing unit may be performed in the increasing order or in the decreasing order, and the adjacent groups should be sequenced in different orders.
Wherein, the sequencing process of the second group dividing unit needs to be performed according to a certain granularity. The granularity of the cyclic shift of Group g is Pg={P1g, P2g, . . . , Psg} and Pig<Pi+1g, thus, (1) the sequencing performed in the increasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Pi+1g, and larger than or equal to Pig, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than P1g, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg; (2) the sequencing performed in the decreasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Ps−i+2g, and larger than or equal to Ps−i+1g, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than P1g.
Wherein, the maximum cyclic shift of the ZC sequences is NCS=min(du,NZC−2·du) wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of the ZC sequence. The distance between the correlation peak and the correlation peak alias thereof is




  du
  =
  
    {
    
      
        
          
            
              
                
                  
                    m
                    ·
                    
                      N
                      ZC
                    
                  
                  -
                  1
                
                u
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ≤
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
        
          
            
              
                
                  N
                  ZC
                
                -
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              >
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
      
      ,
    
  




wherein, u is the serial number of the ZC sequence, and m is the minimum positive integer which makes





  
    
      m
      ·
      
        N
        ZC
      
    
    -
    1
  
  u




a positive integer. Wherein, the sequence dividing unit can divide a plurality of ZC sequences, being sequenced after the first sequencing, into two groups according to the cubic metrics of Quadrature Phase Shift Keying.

The descriptions above are only preferable embodiments of the present invention, which are not used to restrict the present invention. For those skilled in to the art, the present invention may have various changes and variations. Any amendments, equivalent substitutions, improvements etc. within the spirit and principle of the present invention are all included in the scope of the claims of the present invention.

## Claims

1. A method for sequencing Zadoff-Chu (ZC) sequences of random access channel, comprising the following steps:
Step 202, dividing, by a first group dividing unit, Nq ZC sequences into a plurality of groups according to a cubic metrics of the ZC sequences, wherein 1<=Nq<=Nzc−1, Nzc is the length of the ZC sequence;
Step 204, sequencing, by a second group dividing unit, the ZC sequences, according to a maximum cyclic shift supported by the ZC sequences under a high speed circumstance, within each group to form a plurality of sub-groups; and
Step 206, sequencing, by a sequencing unit, the ZC sequences within each of said plurality of sub-groups according to the cubic metrics of the ZC sequences, wherein, adjacent sub-groups in the same group are sequenced in different orders, while the sub-groups at the boundary of two adjacent groups are sequenced in the same order;
wherein, said maximum cyclic shift NCS=min(du,NZC−2·du), wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of said ZC sequence.

2. The method for sequencing the ZC sequences of the random access channel according to claim 1, wherein, said Nq ZC sequences are divided into G groups, wherein, 1≦G≦Nq, the relation between the serial number of each of said plurality of groups and the cubic metrics of the ZC sequences in each of said plurality of groups is: the cubic metrics of the ZC sequences in Group i are smaller than the cubic metrics of the ZC sequences in Group i+1, or the cubic metrics of the ZC sequences in Group i are larger than the cubic metrics of the ZC sequences in Group i+1.

3. The method for sequencing the ZC sequences of the random access channel according to claim 1, wherein, said Nq ZC sequences are divided into two groups according to the cubic metrics of Quadrature Phase Shift Keying.

4. The method for sequencing the ZC sequences of the random access channel according to claim 1, wherein, in Step 202, firstly, said Nq ZC sequences are sequenced, in decreasing order or in increasing order, according to the cubic metrics of the ZC sequences, and then, a sequencing result is divided into a plurality of groups according to one or more cyclic shift thresholds.

5. The method for sequencing the ZC sequences of the random access channel according to claim 1, wherein, in Step 204, the sequencing is performed in increasing order or in decreasing order, and the adjacent groups are sequenced in different orders.

6. The method for sequencing the ZC sequences of the random access channel according to claim 1, wherein, in Step 204, the sequencing is performed according to a preset granularity.

7. The method for sequencing the ZC sequences of the random access channel according to claim 5, wherein, a granularity of the cyclic shift of Group g is Pg={P1g, P2g, . . . , Psg}, and Pig<Pi+1g, and the sequencing performed in the increasing order means: when 1<i<s, the maximum cyclic shift supported by each ZC sequence in Sub-group i under the high speed circumstance is smaller than Pi+1g, and larger than or equal to Pig, when i=1, the maximum cyclic shift supported by each ZC sequence in Sub-group i under the high speed circumstance is smaller than P1g, when i=s, the maximum cyclic shift supported by each ZC sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, and the sequencing performed in the decreasing order means: when 1<i<s, the maximum cyclic shift supported by each ZC sequence in Sub-group i under the high speed circumstance is smaller than Ps−i+2g, and larger than or equal to Ps−i+1g, when i=1, the maximum cyclic shift supported by each ZC sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, when i=s, the maximum cyclic shift supported by each ZC sequence in Sub-group i under the high-speed circumstance is smaller than P1g.

8. The method for sequencing the ZC sequences of the random access channel according to claim 1, wherein, said distance between the correlation peak and the correlation peak alias thereof is




  du
  =
  
    {
    
      
        
          
            
              
                
                  
                    m
                    ·
                    
                      N
                      ZC
                    
                  
                  -
                  1
                
                u
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ≤
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
        
          
            
              
                
                  N
                  ZC
                
                -
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              >
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
      
      ,
    
  




wherein, u is the serial number of said ZC sequence, and m is the minimum positive integer which makes




  
    
      m
      ·
      
        N
        ZC
      
    
    -
    1
  
  u




a positive integer.

9. The method for sequencing the ZC sequences of the random access channel according to claim 2, wherein, said maximum cyclic shift NCS=min(du, NZC−2·du) wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of said ZC sequence.

10. The method for sequencing the ZC sequences of the random access channel according to claim 3, wherein, said maximum cyclic shift NCS=min(du, NZC−2·du) wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of said ZC sequence.

11. A device for sequencing Zadoff-Chu (ZC) sequences of random access channel comprising:
a first group dividing unit, configured to divide Nq ZC sequences into a plurality of groups according to a cubic metrics of the ZC sequences of the random access channel, wherein 1<=Nq<=Nzc−1, Nzc is the length of the ZC sequence;
a second group dividing unit, configured to sequence the ZC sequences within each group to form a plurality of sub-groups, according to the maximum cyclic shift supported by the ZC sequences under a high speed circumstance; and
a sequencing unit, configured to sequence the ZC sequences in each of said plurality of sub-groups according to the cubic metrics of the ZC sequences, wherein, adjacent sub-groups in the same group are sequenced in different orders, while the sub-groups at the boundary of two adjacent groups are sequenced in the same order;
wherein, said maximum cyclic shift NCS=min(du,NZC−2·du), wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of said ZC sequence.

12. The device for sequencing the ZC sequences of the random access channel according to claim 11, wherein, said first group dividing unit divides said Nq ZC sequences into G groups, wherein, 1≦G≦Nq, the relation between the serial number of each of said plurality of groups and the cubic metrics of the ZC sequences in each of said plurality of groups is: the cubic metrics of the ZC sequences in Group i are smaller than the cubic metrics of the ZC sequences in Group i+1, or the cubic metrics of the ZC sequences in Group i are larger than the cubic metrics of the ZC sequences in Group i+1.

13. The device for sequencing the ZC sequences of the random access channel according to claim 11, wherein, said first group dividing unit divides said Nq ZC sequences into two groups using the cubic metrics of Quadrature Phase Shift Keying as a threshold.

14. The device for sequencing the ZC sequences of the random access channel according to claim 11, wherein, said second group dividing unit performs the sequencing of the ZC sequences in each group in increasing order or in decreasing order, and the adjacent groups are sequenced in different orders.

15. The device for sequencing the ZC sequences of the random access channel according to claim 11, wherein, said second group dividing unit performs the sequencing according to a preset granularity.

16. The device for sequencing the ZC sequences of the random access channel according to claim 14, wherein, a granularity of the cyclic shift of Group g is Pg={P1g, P2g, . . . , Psg}, and Pig<Pi+1g, performing the sequencing in the increasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Pi+1g, and larger than or equal to Pig, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed g circumstance is smaller than P1g, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, performing the sequencing in the decreasing order means: when 1<i<s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than Ps−i+2g, and larger than or equal to Ps−i+1g, when i=1, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is larger than or equal to Psg, when i=s, the maximum cyclic shift supported by each sequence in Sub-group i under the high speed circumstance is smaller than p1g.

17. The device for sequencing the ZC sequences of the random access channel according to claim 11, wherein, said distance between the correlation peak and the correlation peak alias thereof is




  du
  =
  
    {
    
      
        
          
            
              
                
                  
                    m
                    ·
                    
                      N
                      ZC
                    
                  
                  -
                  1
                
                u
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ≤
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
        
          
            
              
                
                  N
                  ZC
                
                -
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              ,
            
          
          
            
              
                when
                ⁢
                
                  
                
                ⁢
                
                  
                    
                      m
                      ·
                      
                        N
                        ZC
                      
                    
                    -
                    1
                  
                  u
                
              
              >
              
                floor
                ⁡
                
                  (
                  
                    N
                    /
                    2
                  
                  )
                
              
            
          
        
      
      ,
    
  




wherein, u is the serial number of said ZC sequence, and m is the minimum positive integer which makes




  
    
      m
      ·
      
        N
        ZC
      
    
    -
    1
  
  u




a positive integer.

18. The device for sequencing the ZC sequences of the random access channel according to claim 12, wherein, said maximum cyclic shift NCS=min(du, NZC−2·du) wherein, du is the distance between a correlation peak and a correlation peak alias thereof, and NZC is the length of said ZC sequence.